Self-Sharpening of Thin Tungsten Electrode in Single, High-Current Discharge: Its Dynamics and Mechanism
✍ Scribed by Yoshiro Ito; Rie Tanabe; Naotake Mohri
- Publisher
- International Academy for Production Engineering
- Year
- 2007
- Tongue
- English
- Weight
- 917 KB
- Volume
- 56
- Category
- Article
- ISSN
- 0007-8506
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✦ Synopsis
Self-sharpening of a thin tungsten electrode occurs in single, high-current discharge. This phenomenon has been observed with a custom-made, high-speed imaging system. The system allowed us to take one hundred images of the electrode shape during and after the discharge with 16 μs intervals. The following selfsharpening mechanism has been proposed based on observations: (1) During the discharge, when the melt front descends towards the axis of the electrode, while the melt forms a sphere and moves along it due to the surface tension. (2) The melt continues moving even after the discharge, revealing a needle-shaped unmelted part and then solidifies. Detailed studies of discharge conditions to the diameter of the needle-shape formed by the process have been carried out. Results supporting the proposed mechanism are obtained.